Substrate Processing Apparatus And Substrate Processing Method

ABSTRACT

A substrate processing apparatus comprises a substrate holding mechanism, a process liquid supplying mechanism supplying a process liquid, a first guide portion around the substrate holding mechanism having an upper edge portion extending toward the rotation axis for guiding scattered process to flow down, a second guide portion provided around the substrate holding mechanism outside the first guide portion and having an upper edge portion extending toward the rotation axis as vertically overlapping with the upper edge portion of the first guide portion for further guiding the scattered process liquid to flow down, a recovery channel provided outside and integrally with the first guide portion for recovering the process liquid guided by the second guide portion, and a driving mechanism for moving up and down the first guide portion and the second guide portion independently of each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This present divisional application claims benefit to Ser. No.11/396,700, filed Mar. 31, 2006, and claims priority to JP 2005-103201,filed Mar. 31, 2005, JP 2005-103202, filed Mar. 31, 2005 and JP2005-103203, filed Mar. 31, 2005, which are incorporated herein in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate processing apparatus and asubstrate processing method for processing a substrate. Examples of thesubstrate to be processed include semiconductor wafers, glass substratesfor liquid crystal display devices, glass substrates for plasma displaydevices, substrates for optical disks, substrates for magnetic disks,substrates for magneto-optical disks, and substrates for photo masks.

2. Description of Related Art

In production processes for semiconductor devices and liquid crystaldisplay devices, a single substrate processing apparatuses is used forprocessing a surface of a substrate a semiconductor wafer, a glasssubstrate for a liquid crystal display panel or the like with a processliquid. For reduction of the consumption of the process liquid, some ofthe substrate processing apparatuses of this type are adapted to recoverthe process liquid used for the process of the substrate and reuse therecovered process liquid for the subsequent process.

Such a substrate processing apparatus adapted to reuse the processliquid includes, for example, a spin chuck which horizontally holds androtates a substrate, a bottomed hollow cylindrical cup in which the spinchuck is accommodated, and a splash guard provided vertically movablywith respect to the cup.

The cup has an annular drain channel provided around the spin chuck. Thecup further has three annular recovery channels triply concentricallyprovided around the drain channel. The drain channel is connected to awaste liquid drain for draining the process liquid. The recoverychannels are each connected to a recovery drain for guiding the processliquid to a recovery tank.

The splash guard includes four guards vertically and radially overlappedwith each other. The guards each have a substantially rotationallysymmetrical shape about the rotation axis of the substrate. Upper edgeportions of the guards are each inclined upward toward the rotation axisof the substrate. Upper edges of the guards are located in predeterminedspaced relation on a cylindrical plane having a center axis aligningwith the rotation axis of the substrate. The guards are respectivelyassociated with the recovery channels and the drain channel, and loweredges of the guards are respectively inserted in the recovery channelsand the drain channel. That is, the uppermost guard (first guard) isassociated with the outermost recovery channel (first channel), and thelower edge of the first guard is inserted in the first recovery channel.A guard (second guard) immediately below the first guard is associatedwith a recovery channel (second channel) disposed inwardly adjacent tothe first recovery channel, and the lower edge of the second guard isinserted in the second recovery channel. A guard (third guard)immediately below the second guard is associated with the innermostrecovery channel (third recovery channel inwardly adjacent to the secondrecovery channel), and the lower edge of the third guard is inserted inthe third recovery channel. The lowermost guard (fourth guard) isassociated with the drain channel, and the lower edge of the fourthguard is inserted in the drain channel.

A first recovery port is defined between the upper edge of the firstguard and the upper edge of the second guard for introducing the processliquid scattered from the substrate into the first recovery channel. Asecond recovery port is defined between the upper edge of the secondguard and the upper edge of the third guard for introducing the processliquid scattered from the substrate into the second recovery channel. Athird recovery port is defined between the upper edge of the third guardand the upper edge of the fourth guard for introducing the processliquid scattered from the substrate into the third recovery channel. Adrain port is defined between the fourth guard and a bottom surface ofthe cup for introducing the process liquid scattered from the substrateinto the drain channel.

A lift driving mechanism, for example, including a ball screw mechanismand the like is connected to the splash guard. The four guards are movedup and down together by the lift driving mechanism.

In the substrate processing apparatus having the aforesaid construction,plural types of process liquids are sequentially supplied to the surfaceof the substrate to treat the substrate surface sequentially with theplural types of process liquids. Further, the plural types of processliquids used for the processes are separately recovered.

More specifically, the substrate surface is processed with a firstprocess liquid by supplying the first process liquid to the substratesurface while rotating the substrate by the spin chuck. The firstprocess liquid supplied to the substrate surface is scattered radiallyoutward from the peripheral edge of the substrate by a centrifugal forcegenerated by the rotation of the substrate. At this time, the splashguard is vertically moved to bring the first recovery port into opposedrelation to a peripheral edge surface of the substrate, whereby thefirst process liquid scattered from the peripheral edge of the substrateis introduced into the first recovery port. Then, the first processliquid is recovered into the recovery tank through the recovery drain.Similarly, when a second process liquid is supplied to the substratesurface, the second recovery port is opposed to the peripheral edgesurface of the substrate to recover the second process liquid scatteredfrom the substrate. When a third process liquid is supplied to thesubstrate surface, the third recovery port is opposed to the peripheraledge surface of the substrate to recover the third process liquidscattered from the substrate.

Further, a rinsing operation is performed to rinse the substrate surfacewith pure water (process liquid) by supplying the pure water to thesubstrate surface while rotating the substrate by the spin chuck. Atthis time, the drain port is opposed to the peripheral edge surface ofthe substrate, whereby the pure water used for the rinsing of thesubstrate surface is collected in the drain channel and drained from thedrain channel through the waste liquid drain.

However, the substrate processing apparatus having the aforesaidconstruction has several problems.

1. The recovery ports are constantly open. Therefore, even with apredetermined one of the recovery ports and the drain port being opposedto the peripheral edge surface of the substrate, the process liquidscattered from the substrate is liable to enter the other ports(particularly the ports adjacent to the predetermined one port), therebycontaminating the process liquids recovered through the other ports inthe corresponding recovery channels. During the process with the firstprocess liquid, for example, the scattered first process liquid isliable to partly enter the second recovery port even with the firstrecovery port being opposed to the peripheral edge surface of thesubstrate, thereby contaminating the second process liquid recovered inthe second recovery channel. Further, with the first recovery port beingopposed to the peripheral edge surface of the substrate, i.e., with thesplash guard being located at the lowermost position, the lower edges ofthe respective guards are inserted in the drain channel and the recoverchannels to a greater extent, so that gaps between the lower edges ofthe respective guards and the cup are narrowed. Therefore, the processliquids in the recovery channels and the drain channel are liable toflow into the other channels by the capillary phenomenon.

2. When the lowermost drain port is brought into opposed relation to theperipheral edge surface of the substrate, the splash guard should bemoved up a greater distance. Therefore, a greater space should beprovided above the cup, so that the apparatus has a greater height.

3. Where types of process liquids to be recovered are increased, theexisting cup should be replaced with a cup having a correspondinglyincreased number of recovery channels, and the existing splash guardshould be replaced with a splash guard having a correspondinglyincreased number of guards. This inevitably results in a significantcost increase. In addition, the height of the splash guard is increased,thereby the vertical movement distance of the splash guard is furtherincreased. This increases the height of the apparatus.

4. The recovery ports are constantly open. Therefore, when the splashguard is moved up or down for performing the rinsing operationimmediately after the process with the first or second process liquid orperforming the process with the first or second process liquidimmediately after the rinsing operation, the process liquid scatteredfrom the substrate is liable to enter a recovery port disposed betweenthe first or second recovery port and the drain port during the upwardor downward movement of the splash guard, thereby contaminating theprocess liquid to be recovered through that recovery port. When thesplash guard is moved up for performing the rinsing operationimmediately after the process with the second process liquid, forexample, the third recovery port is brought into opposed relation to theperipheral edge surface of the substrate during the upward movement ofthe splash guard. At this time, the second process liquid scattered fromthe substrate is liable to enter the third recovery port, therebycontaminating the third process liquid to be recovered in the thirdrecovery channel.

A conceivable approach to prevention of the contamination of the processliquids is to stop the rotation of the substrate by the spin chuckduring the upward or downward movement of the splash guard. However, ifthe rotation of the substrate is once stopped, it takes time to increasethe rotation speed of the substrate to a predetermined speed (a rotationspeed required for the subsequent process), thereby prolonging thesubstrate process time. This reduces the process throughput. Therefore,the stop of the rotation of the substrate during the upward or downwardmovement of the splash guard is not a preferred approach to theprevention of the contamination of the process liquid.

5. The rinsing operation is performed after the processes with the firstprocess liquid, the second process liquid and the third process liquidare each performed. Therefore, an atmosphere containing a mist of purewater used for washing away the process liquid used for the precedingprocess is produced during the rinsing operation. If such an atmosphereremains in the drain channel and around the substrate, the rinsedsubstrate may be adversely affected. Therefore, the atmosphere aroundthe substrate is preferably sucked through the drain channel so as to beremoved by an evacuation line connected to the drain channel for forcedevacuation of the drain channel.

However, the drain channel atmospherically communicates with therespective recovery channels. Therefore, if the drain channel isforcibly evacuated, the recovery channels are indirectly evacuated,whereby air streams flowing from the recovery ports to the recoverychannels occur. As a result, droplets of the process liquid to bedrained into the drain channel enter the recovery channels from therecovery ports, thereby reducing the purities of the process liquidsrecovered in the respective recovery channels.

SUMMARY OF THE INVENTION

It is a first object of the present invention to provide a substrateprocessing apparatus which prevents a process liquid recovered in arecovery channel from being contaminated with other process liquids(process liquids which should not be recovered in that recoverychannel).

It is a second object of the present invention to provide a substrateprocessing apparatus which has a reduced height.

It is a third object of the present invention to provide a substrateprocessing apparatus which can be modified so as to recover an increasedtypes of process liquids without a significant cost increase.

It is a fourth object of the present invention to provide a substrateprocessing apparatus which, when recovering a process liquid used for asubstrate processing, prevents the process liquid from beingcontaminated with other process liquids without reduction of the processthroughput.

It is a fifth object of the present invention to provide a substrateprocessing method which ensures that a process liquid used for asubstrate process is recovered without contamination of the processliquid with other process liquids and the substrate processing isproperly performed even by reusing the recovered process liquid.

It is a sixth object of the present invention to provide a substrateprocessing apparatus which is capable of forcibly evacuating a drainchannel and yet recovering a process liquid at an improved purity in arecovery channel.

An inventive substrate processing apparatus for achieving the first,second and third objects described above comprises a substrate holdingmechanism which generally horizontally holds a substrate and rotates thesubstrate about a generally vertical rotation axis, a process liquidsupplying mechanism for supplying a process liquid to the substrate heldby the substrate holding mechanism, a first guide portion providedaround the substrate holding mechanism and having an upper edge portionextending toward the rotation axis for guiding the process liquidscattered from the substrate rotated by the substrate holding mechanismto cause the process liquid to flow down, a second guide portionprovided around the substrate holding mechanism outside the first guideportion and having an upper edge portion extending toward the rotationaxis as vertically overlapping with the upper edge portion of the firstguide portion for guiding the process liquid scattered from thesubstrate rotated by the substrate holding mechanism to cause theprocess liquid to flow down, a recovery channel provided outside thefirst guide portion integrally with the first guide portion forrecovering the process liquid guided by the second guide portion, and adriving mechanism for moving up and down the first guide portion and thesecond guide portion independently of each other.

With this arrangement, the first guide portion and the second guideportion doubly surround the substrate holding mechanism. The secondguide portion is disposed outside the first guide portion with the upperedge portion thereof vertically overlapping with the upper edge portionof the first guide portion. The recovery channel for recovering theprocess liquid guided by the second guide portion is provided outsidethe first guide portion integrally with the first guide portion.

The first guide portion and the second guide portion can be moved up anddown independently of each other by the driving mechanism. Therefore,the first guide portion and the second guide portion are verticallymoved so as to locate the upper edge portions of the first guide portionand the second guide portion at a lower level than the substrate, tolocate the upper edge portion of the first guide portion at a lowerlevel than the substrate and locate the upper edge portion of the secondguide portion at a higher level than the substrate, or to locate theupper edge portions of the first guide portion and the second guideportion at a higher level than the substrate.

Where the upper edge portion of the first guide portion is located at alower level than the substrate and the upper edge portion of the secondguide portion is located at a higher level than the substrate, anopening is defined between the upper edge portion of the first guideportion and the upper edge portion of the second guide portion inopposed relation to a peripheral edge surface of the substrate.Therefore, the process liquid scattered from the substrate is introducedinto the opening between the upper edge portion of the first guideportion and the upper edge portion of the second guide portion, and theintroduced process liquid is guided by the second guide portion to berecovered in the recovery channel. By moving up the first guide portionfrom this state with the second guide portion kept still to locate theupper edge portions of the first guide portion and the second guideportion at a higher level than the substrate, the first guide portion isbrought into opposed relation to the peripheral edge surface of thesubstrate. Thus, the process liquid scattered from the substrate can beguided by the first guide portion to flow down.

When the process liquid is to be guided by the first guide portion, thefirst guide portion is moved up to the vicinity of the second guideportion with a very small gap being defined between the upper edgeportion thereof and the upper edge portion of the second guide portion.Thus, the process liquid scattered from the substrate is guided by thefirst guide portion to flow down, while being prevented from intrudinginto the gap between the upper edge portion of the first guide portionand the upper edge portion of the second guide portion. In addition, thefirst guide portion and the second guide portion do not contact eachother, so that a problem associated with particles which may otherwisebe generated by the contact can be eliminated. Further, the processliquid is isolated from the recovery channel by the first guide portionwhen being guided by the first guide portion. Hence, there is nopossibility that the process liquid flows into the recovery channel bythe capillary phenomenon. Therefore, a process liquid different from theprocess liquid to be recovered in the recovery channel is prevented fromentering the recovery channel. As a result, the purity of the processliquid recovered in the recovery channel can be improved.

When the process liquid is to be guided by the first guide portion,there is no particular need to move up the second guide portion, but thesecond guide portion may be located at the same position as assumed forguiding the process liquid. Hence, there is no need to provide a greaterspace above the recovery channel, thereby the height of the apparatus iscorrespondingly reduced.

Where the types of process liquids to be recovered is increased, a guideportion is additionally provided around the second guide portion outsidethe second guide portion, and a recovery channel for recovering aprocess liquid to be guided by the additional guide portion isadditionally provided integrally with the second guide portion.Therefore, the existing first guide portion and the existing recoverychannel can be used, so that a significant cost increase can be avoided.That is, the apparatus can be thus modified so as to recover anincreased types of process liquids without a significant cost increase.Further, when the process liquid is to be guided by the first guideportion, there is no particular need to move up the additional guideportion, thereby the increase in the height of the apparatus is avoided.

The inventive substrate processing apparatus for achieving the first tothird objects described above preferably further comprises an intrusionpreventing portion for preventing the process liquid scattered from thesubstrate rotated by the substrate holding mechanism from intruding intoa space between the first guide portion and the second guide portionwhen the process liquid is guided by the first guide portion.

The provision of the intrusion preventing portion makes it possible toguide the process liquid scattered from the substrate by the first guideportion to cause the process liquid to flow down while assuredlypreventing the process liquid from intruding into the space between thefirst guide portion and the second guide portion. Therefore, a processliquid different from the process liquid to be recovered in the recoverychannel is assuredly prevented from entering the recovery channel. As aresult, the purity of the process liquid recovered in the recoverychannel can be further improved.

In this case, the intrusion preventing portion is preferably a part ofthe upper edge portion of the second guide portion folded downward.

With this arrangement, the intrusion preventing portion extends downwardfrom the upper edge of the second guide portion, so that the processliquid scattered from the substrate is prevented from flowing around theintrusion preventing portion and intruding into the space between thefirst guide portion and the second guide portion. Therefore, when theprocess liquid guided by the second guide portion is recovered, therecovered process liquid is assuredly prevented from being contaminatedwith other process liquids. As a result, the purity of the recoveredprocess liquid can be further improved. In addition, the intrusionpreventing portion is unitary with the second guide portion, so that theconstruction of the apparatus is simplified.

An inventive substrate processing apparatus for achieving the fourthobject described above comprises a substrate holding mechanism whichgenerally horizontally holds a substrate and rotates the substrate abouta generally vertical rotation axis, a process liquid supplying mechanismfor supplying a process liquid to the substrate held by the substrateholding mechanism, a first guide portion provided around the substrateholding mechanism and having an upper edge portion extending toward therotation axis for guiding the process liquid scattered from thesubstrate rotated by the substrate holding mechanism to cause theprocess liquid to flow down, a second guide portion provided around thesubstrate holding mechanism outside the first guide portion and havingan upper edge portion extending toward the rotation axis as verticallyoverlapping with the upper edge portion of the first guide portion forguiding the process liquid scattered from the substrate rotated by thesubstrate holding mechanism to cause the process liquid to flow down, adriving mechanism for moving up and down the first guide portion and thesecond guide portion independently of each other, and vertical movementcontrolling means which controls the driving mechanism to move up anddown the first guide portion and the second guide portion insynchronization.

With this arrangement, the first guide portion and the second guideportion doubly surround the substrate holding mechanism. The secondguide portion is disposed outside the first guide portion with the upperedge portion thereof vertically overlapping with the upper edge portionof the first guide portion. Although the driving mechanism is adapted tomove up and down the first guide portion and the second guide portionindependently of each other, the vertical movement controlling means isprovided for moving up and down the first guide portion and the secondguide portion in synchronization.

Thus, the first guide portion and the second guide portion can be movedup and down in synchronization (simultaneously at the same speed) whilebeing kept in close relation with a very small gap being defined betweenthe upper edge portions of the first and second guide portions. Wherethe process liquid scattered from the substrate is guided by the firstguide portion with the upper edge portions of the first and second guideportions being located at a higher level than the substrate and, fromthis state, the first guide portion and the second guide portion aremoved down in synchronization with the very small gap being definedbetween the upper edge portions of the first and second guide portionsto locate the upper edge portions of the first and second guide portionsat a lower level than the substrate, for example, the process liquidscattered from the substrate is prevented from intruding into the gapbetween the upper edge portions of the first and second guide portionseven with the substrate kept rotated by the substrate holding mechanism.Therefore, when the process liquid guided by the second guide portion isrecovered, the recovered process liquid is prevented from beingcontaminated with other process liquids (e.g., the process liquid to beguided by the first guide portion) without reduction of the processthroughput. As a result, the purity of the recovered process liquid canbe improved.

The inventive substrate processing apparatus for achieving the fourthobject described above preferably further comprises an intrusionpreventing portion for preventing the process liquid scattered from thesubstrate rotated by the substrate holding mechanism from intruding intoa space between the first guide portion and the second guide portionwhen the process liquid is guided by the first guide portion.

With the provision of the intrusion preventing portion, the processliquid scattered from the substrate is assuredly prevented fromintruding into the space between the first guide portion and the secondguide portion when the process liquid is guided by the first guideportion. Therefore, when the process liquid guided by the second guideportion is recovered, the recovered process liquid is assuredlyprevented from being contaminated with the other process liquids. As aresult, the purity of the recovered process liquid can be furtherimproved.

In this case, the intrusion preventing portion is preferably a part ofthe upper edge portion of the second guide portion folded downward.

With this arrangement, the intrusion preventing portion extends downwardfrom the upper edge of the second guide portion, so that the processliquid scattered from the substrate is prevented from flowing around theintrusion preventing portion and intruding into the space between thefirst guide portion and the second guide portion. Therefore, when theprocess liquid guided by the second guide portion is recovered, therecovered process liquid is assuredly prevented from being contaminatedwith the other process liquids. As a result, the purity of the recoveredprocess liquid can be further improved. In addition, the intrusionpreventing portion is unitary with the second guide portion, so that theconstruction of the apparatus is simplified.

The inventive substrate processing apparatus for achieving the fourthobject described above may further comprise a third guide portionprovided around the substrate holding mechanism outside the second guideportion and having an upper edge portion extending toward the rotationaxis as vertically overlapping with the upper edge portion of the secondguide portion for guiding the process liquid scattered from thesubstrate rotated by the substrate holding mechanism to cause theprocess liquid to flow down, wherein the vertical movement controllingmeans controls the driving mechanism to move up the first guide portionand the second guide portion in synchronization when a process liquidguiding state is shifted from a state in which the process liquidscattered from the substrate rotated by the substrate holding mechanismis guided by the third guide portion to a state in which the processliquid is guided by the first guide portion.

In the state in which the process liquid scattered from the substrate isguided by the third guide portion, the upper edge portions of the firstguide portion and the second guide portion are located at a lower levelthan the substrate, and the upper edge portion of the third guideportion is located at a higher level than the substrate. On the otherhand, in the state in which the process liquid scattered from thesubstrate is guided by the first guide portion, the upper edge portionsof the first guide portion, the second guide portion and the third guideportion are located at a higher level than the substrate. When theprocess liquid guiding state is to be shifted from the state in whichthe process liquid scattered from the substrate is guided by the thirdguide portion to the state in which the process liquid is guided by thefirst guide portion, the first guide portion and the second guideportion are moved up in synchronization with the very small gap beingdefined between the upper edge portions thereof. Thus, the processliquid scattered from the substrate is prevented from intruding into thegap between the upper edge portions of the first and second guideportions even with the substrate kept rotated by the substrate holdingmechanism. Therefore, when the process liquid guided by the second guideportion is recovered, the recovered process liquid is prevented frombeing contaminated with the process liquid to be guided by the thirdguide portion without reduction of the process throughput. As a result,the purity of the recovered process liquid can be improved.

In this case, the upper edge portion of the third guide portionpreferably has a portion folded downward for preventing the processliquid scattered from the substrate rotated by the substrate holdingmechanism from intruding into a space between the second guide portionand the third guide portion when the process liquid is guided by thefirst guide portion or the second guide portion.

With the provision of the folded portion, the process liquid scatteredfrom the substrate is assuredly prevented from intruding into the spacebetween the second guide portion and the third guide portion when theprocess liquid is guided by the first guide portion or the second guideportion. Therefore, when the process liquid guided by the third guideportion is recovered, the recovered process liquid is prevented frombeing contaminated with the process liquid to be guided by the firstguide portion or the second guide portion. As a result, the purity ofthe recovered process liquid can be improved. Further, the foldedportion is unitary with the third guide portion, so that theconstruction of the apparatus is simplified.

Alternatively, the inventive substrate processing apparatus forachieving the fourth object described above may further comprise a thirdguide portion provided around the substrate holding mechanism outsidethe second guide portion and having an upper edge portion extendingtoward the rotation axis as vertically overlapping with the upper edgeportion of the second guide portion for guiding the process liquidscattered from the substrate rotated by the substrate holding mechanismto cause the process liquid to flow down, wherein the first guideportion, the second guide portion and the third guide portion are moveddown in synchronization when a process liquid guiding state is shiftedfrom a state in which the process liquid scattered from the substraterotated by the substrate holding mechanism is guided by the first guideportion to a state in which the process liquid flows over the firstguide portion, the second guide portion and the third guide portion tobe drained to the outside.

In the state in which the process liquid scattered from the substrate isguided by the first guide portion, the upper edge portions of the firstguide portion, the second guide portion and the third guide portion arelocated at a higher level than the substrate. When the process liquidguiding state is to be shifted from this state to the state in which theprocess liquid flows over the first guide portion, the second guideportion and the third guide portion to be drained to the outside, thefirst guide portion, the second guide portion and the third guideportion are moved down in synchronization with very small gaps beingdefined between the upper edge portions of the first and second guideportions and between the upper edge portions of the second and thirdguide portions. Thus, the process liquid scattered from the substrate isprevented from intruding into the gaps between the upper edge portionsof the first and second guide portions and between the upper edgeportions of the second and third guide portions even with the substratekept rotated by the substrate holding mechanism. Therefore, when theprocess liquid guided by the second guide portion or the third guideportion is recovered, the recovered process liquid is prevented frombeing contaminated with a process liquid to be spun out withoutreduction of the process throughput. As a result, the purity of therecovered process liquid can be improved.

In this case, the upper edge portion of the third guide portionpreferably has a portion folded downward for preventing the processliquid scattered from the substrate rotated by the substrate holdingmechanism from intruding into a space between the second guide portionand the third guide portion when the process liquid is guided by thefirst guide portion or the second guide portion.

With the provision of the folded portion, the process liquid scatteredfrom the substrate is assuredly prevented from intruding into the spacebetween the second guide portion and the third guide portion when theprocess liquid is guided by the first guide portion or the second guideportion. Therefore, when the process liquid guided by the third guideportion is recovered, the recovered process liquid is prevented frombeing contaminated with the process liquid to be guided by the firstguide portion or the second guide portion. As a result, the purity ofthe recovered process liquid can be improved. Further, the foldedportion is unitary with the third guide portion, so that theconstruction of the apparatus is simplified.

An inventive substrate processing method for achieving the fifth objectdescribed above is a method for processing a substrate in a substrateprocessing apparatus including a substrate holding mechanism whichgenerally horizontally holds the substrate and rotates the substrateabout a generally vertical rotation axis, and a first guide portion, asecond guide portion and a third guide portion provided around thesubstrate holding mechanism in an independently vertically movablemanner for guiding a process liquid scattered from the substrate rotatedby the substrate holding mechanism to cause the process liquid to flowdown and respectively having upper edge portions extending toward therotation axis as vertically overlapping with each other. The methodcomprises the steps of: rotating the substrate by the substrate holdingmechanism; supplying the process liquid to the substrate in thesubstrate rotating step; and simultaneously moving up the first guideportion and the second guide portion in the process liquid supplyingstep to shift a process liquid guiding state from a state in which theprocess liquid scattered from the substrate rotated by the substrateholding mechanism is guided by the third guide portion to a state inwhich the process liquid is guided by the first guide portion.

According to this method, where the process liquid guided by the secondguide portion is recovered, the recovered process liquid is preventedfrom being contaminated with the process liquid to be guided by thethird guide portion without reduction of the process throughput. As aresult, the purity of the recovered process liquid can be improved.Therefore, the process of the substrate can be properly performed evenby reusing the recovered process liquid.

An inventive substrate processing method for achieving the fifth objectdescribed above is a method for processing a substrate in a substrateprocessing apparatus including a substrate holding mechanism whichgenerally horizontally holds the substrate and rotates the substrateabout a generally vertical rotation axis, and a first guide portion, asecond guide portion and a third guide portion provided around thesubstrate holding mechanism in an independently vertically movablemanner for guiding a process liquid scattered from the substrate rotatedby the substrate holding mechanism to cause the process liquid to flowdown and respectively having upper edge portions extending toward therotation axis as vertically overlapping with each other. The methodcomprises the steps of: rotating the substrate by the substrate holdingmechanism; supplying the process liquid to the substrate in thesubstrate rotating step; simultaneously moving up the first guideportion and the second guide portion in the process liquid supplyingstep to shift a process liquid guiding state from a state in which theprocess liquid scattered from the substrate rotated by the substrateholding mechanism is guided by the third guide portion to a state inwhich the process liquid is guided by the first guide portion; andsimultaneously moving down the first guide portion, the second guideportion and the third guide portion in the process liquid supplying stepto shift the process liquid guiding state from the state in which theprocess liquid scattered from the substrate rotated by the substrateholding mechanism is guided by the first guide portion to a state inwhich the process liquid flows over the first guide portion, the secondguide portion and the third guide portion to be drained to the outside.

According to this method, when the process liquid guided by the secondguide portion or the third guide portion is recovered, the recoveredprocess liquid is prevented from being contaminated with the processliquid to be guided by the third guide portion without reduction of theprocess throughput. As a result, the purity of the recovered processliquid can be improved. Therefore, the process of the substrate can beproperly performed even by reusing the recovered process liquid.

An inventive substrate processing apparatus for achieving the sixthobject described above comprises a substrate holding mechanism whichgenerally horizontally holds a substrate and rotates the substrate, aprocess liquid supplying mechanism for selectively supplying a firstprocess liquid and a second process liquid to the substrate held by thesubstrate holding mechanism, a first guide portion provided around thesubstrate holding mechanism for guiding the first process liquidscattered from the substrate rotated by the substrate holding mechanismto cause the first process liquid to flow down, a second guide portionprovided around the substrate holding mechanism for guiding the secondprocess liquid scattered from the substrate rotated by the substrateholding mechanism to cause the second process liquid to flow down, adrain channel for draining the first process liquid guided by the firstguide portion, a recovery channel for recovering the second processliquid guided by the second guide portion, and an evacuation mechanismfor forcibly evacuating the drain channel. In this substrate processingapparatus, the drain channel and the recovery channel areatmospherically isolated from each other and the recovery channel is notforcibly evacuated.

With this arrangement, the drain channel is forcibly evacuated, so thatthe atmosphere around the substrate is sucked into the drain channelthereby to be removed when the first process liquid is drained into thedrain channel. Further, the drain channel and the recovery channel areatmospherically isolated from each other, and the recovery channel isnot forcibly evacuated. Even if the drain channel is evacuated, no airstream enters the recovery channel without the evacuation of therecovery channel. Therefore, droplets of the first process liquid areprevented from entering the recovery channel. This improves the purityof the process liquid recovered in the recovery channel while permittingthe forced evacuation of the drain channel.

In this case, the first guide portion is preferably movable to a firstposition at which a relatively small gap is defined between the firstguide portion and the substrate holding mechanism and to a secondposition at which a relatively large gap is defined between the firstguide portion and the substrate holding mechanism and, when the secondprocess liquid is guided by the second guide portion, the first guideportion is preferably located at the first position.

When the second process liquid is guided by the second guide portion,i.e., when the second process liquid is recovered in the recoverychannel, the gap between the first guide portion and the substrateholding mechanism is thus narrowed. Therefore, even when the drainchannel is evacuated, the second process liquid is prevented from beingsucked into the drain channel from the gap between the first guideportion and the substrate holding mechanism by a suction force appliedfor the evacuation. Thus, the recovery rate of the second process liquidcan be improved.

The first guide portion is preferably provided between the drain channeland the recovery channel integrally with the drain channel and therecovery channel.

In this case, a simple arrangement including the first guide portionprovided between the drain channel and the recovery channel integrallywith the drain channel and the recovery channel makes it possible toatmospherically isolate the drain channel and the recovery channel fromeach other and, hence, to prevent the evacuation of the recovery channelwhich may otherwise occur due to the evacuation of the drain channel. Asa result, the purity of the process liquid recovered in the recoverychannel can be improved without complication of the construction and anassociated cost increase.

The inventive substrate processing apparatus for achieving the sixthobject described above preferably further comprises an isolation memberprovided between the drain channel and the recovery channel andconnected to the first guide portion, the isolation member beingcooperative with the first guide portion to atmospherically isolate thedrain channel and the recovery channel from each other.

Even when the first guide portion is provided separately from the drainchannel and the recovery channel, a simple arrangement including theisolation member provided between the drain channel and the recoverychannel and connected to the first guide portion makes it possible toatmospherically isolate the drain channel and the recovery channel fromeach other and, hence, to prevent the evacuation of the recovery channelwhich may otherwise occur due to the evacuation of the drain channel. Asa result, the purity of the process liquid recovered in the recoverychannel can be improved without complication of the construction and anassociated cost increase.

The foregoing and other objects, features and effects of the presentinvention will become more apparent from the following detaileddescription of preferred embodiments with reference to the attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating a construction of a substrateprocessing apparatus according to an embodiment of the presentinvention;

FIG. 2 is a sectional view of a spin chuck and a cup taken along asectional line A-A in FIG. 1;

FIG. 3 is a sectional view of the spin chuck and the cup taken along asectional line B-B in FIG. 1; FIG. 4 is a sectional view of the spinchuck and the cup taken along a sectional line C-C in FIG. 1;

FIG. 5 is a sectional view of a ball screw mechanism;

FIG. 6 is a simplified plan view illustrating an arrangement fortransmitting driving forces to a first lift mechanism, a second liftmechanism and a third lift mechanism;

FIG. 7 is a schematic sectional view for explaining positions of aninner structural member, a middle structural member and an outerstructural member during a wafer loading operation and a wafer dryingoperation;

FIG. 8 is a schematic sectional view for explaining positions of theinner structural member, the middle structural member and the outerstructural member during a wafer process with a first chemical;

FIG. 9 is a schematic sectional view for explaining positions of theinner structural member, the middle structural member and the outerstructural member during a rinsing operation;

FIG. 10 is a schematic sectional view for explaining positions of theinner structural member, the middle structural member and the outerstructural member during a wafer process with a second chemical; and

FIG. 11 is a simplified sectional view illustrating a construction of asubstrate processing apparatus according to another embodiment of thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a plan view illustrating a construction of a substrateprocessing apparatus according to an embodiment of the presentinvention.

The substrate processing apparatus is adapted to perform a cleaningprocess on a wafer W (an example of a substrate) by supplying a firstchemical, a second chemical and pure water (deionized water) as aprocess liquid in a predetermined order to the wafer W. The substrateprocessing apparatus includes a spin chuck 1 for generally horizontallyholding the wafer W and rotating the wafer W about a generally verticalrotation axis C (see FIG. 2), a cup 2 in which the spin chuck 1 isaccommodated, and a nozzle 3 for selectively supplying the firstchemical, the second chemical and the pure water to a surface (uppersurface) of the wafer W held by the spin chuck 1.

In FIG. 1, the nozzle 3 is disposed at a fixed position obliquely upwardof the spin chuck 1 for supplying the process liquid to a surface of thewafer W from the obliquely upward position, but may be disposed at afixed position on the rotation axis of the wafer W rotated by the spinchuck 1 for supplying the process liquid to the surface of the wafer Wfrom the position vertically upward of the wafer W. Alternatively, aso-called scan nozzle system may be employed in which the nozzle 3 isattached to an arm pivotal within a horizontal plane above the spinchuck 1 (cup 2) and a process liquid supply position on the surface ofthe wafer W is scanned by pivoting the arm. Further, where a shieldplate is disposed in closely opposed relation to the surface of thewafer W during a drying operation to be described later, a processliquid supply port may be provided in a center portion of the shieldplate, so that the process liquid is supplied to the surface of thewafer W from the process liquid supply port. Further, a nozzle forsupplying the first chemical, a nozzle for supplying the second chemicaland a nozzle for supplying the pure water may be separately provided,which are selectively used for supplying the process liquid.

FIG. 2 is a sectional view of the spin chuck 1 and the cup 2 taken alonga sectional line A-A in FIG. 1. FIG. 3 is a sectional view of the spinchuck 1 and the cup 2 taken along a sectional line B-B in FIG. 1. FIG. 4is a sectional view of the spin chuck 1 and the cup 2 taken along asectional line C-C in FIG. 1.

The spin chuck 1 includes a rotation shaft 4 disposed generallyvertically, a disk-shaped spin base 5 fixed to an upper end of therotation shaft 4, and a motor 6 disposed below the spin base 5.

The rotation shaft 4 is a hollow shaft integral with a driving shaft ofthe motor 6. A rear surface process liquid supply pipe 7 extends throughthe inside of the rotation shaft 4. The first chemical, the secondchemical and the pure water are selectively supplied to the rear surfaceprocess liquid supply pipe 7. The rear surface process liquid supplypipe 7 has a rear surface nozzle 8 provided at an upper end thereof forspouting the process liquid (the first chemical, the second chemical orthe pure water) selectively supplied to the rear surface process liquidsupply pipe 7. The rear surface nozzle 8 spouts the process liquidgenerally vertically upward. The process liquid spouted from the rearsurface nozzle 8 is generally vertically incident on a center portion ofthe rear surface of the wafer W held by the spin chuck 1.

The spin base 5 includes an upper cover 9 having a disk shape as seen inplan, and a lower cover 10 having also a disk shape as seen in plan. Theupper cover 9 and the lower cover 10 are fixed to each other by bolts todefine an accommodating space 11 therebetween for accommodating a linkmechanism to be described later. The spin base 5 has a through-hole 12provided in a center portion thereof (center portions of the upper cover9 and the lower cover 10 thereof) as having substantially the same innerdiameter as the rotation shaft 4. An upper end of the rotation shaft 4is connected to the periphery of the through-hole 12, so that aninterior surface of the rotation shaft 4 is continuous with a peripheralsurface of the through-hole 12 with no step. A portion of the rearsurface process liquid supply pipe 7 projects from the upper end of therotation shaft 4, and the projecting portion of the rear surface processliquid pipe 7 is inserted in the through-hole 12.

A plurality of holder members 13 (three holder members 13 in thisembodiment) are disposed generally equiangularly on a peripheral edge ofan upper surface of the spin base 5. The holder members 13 each includea support portion 14 for supporting the wafer W from a lower side, and arestricting portion 15 for restricting a peripheral edge surface of thewafer W. The holder members 13 are coupled to each other by the linkmechanism (not shown) accommodated in the spin base 5. The holdermembers 13 cooperatively hold the wafer W with the restricting portions15 thereof in abutment against the peripheral edge of the wafer Wsupported by the support portions 14 thereof. The holder members 13 aredisengaged from the wafer W with the restricting portions 15 thereofbeing retracted from the peripheral edge of the wafer W.

The motor 6 is disposed on a horizontally extending base 16, andsurrounded by a tubular cover member 17. The cover member 17 has a loweredge fixed to the base 16, and an upper edge portion extending to thevicinity of the lower cover 10 of the spin base 5. A flange 18 isprovided on the upper edge portion of the cover member 17 as generallyhorizontally projecting outward from the cover member 17 and bentdownward.

The cup 2 includes an inner structural member 19, a middle structuralmember 20 and an outer structural member 21 which are vertically movableindependently of each other.

The inner structural member 19 surrounds the spin chuck 1, and has arotationally symmetrical shape about the rotation axis C of the wafer Wto be rotated by the spin chuck 1. The inner structural member 19integrally includes a bottom portion 22 having an annular plan shape, ahollow cylindrical inner wall 23 projecting upward from an innerperipheral edge of the bottom portion 22, a hollow cylindrical outerwall 24 projecting upward from an outer peripheral edge of the bottomportion 22, and a first guide portion 25 projecting upward from aportion thereof between the inner wall 23 and the outer wall 24 andhaving an upper edge portion 25 b smoothly arcuately extending obliquelyupward toward the center thereof (toward the rotation axis C of thewafer W).

The inner wall 23 has a length such as to be accommodated between thecover member 17 and the flange 18 in spaced relation from the covermember 17 and the flange 18 when the inner structural member 19 islocated at the uppermost position (as indicated by a phantom line inFIG. 4).

The outer wall 24 has a length such as to be accommodated between asecond guide portion 48 (lower edge portion 48 a) and an inner wall 50of the middle structural member 20 to be described later in spacedrelation from the second guide portion 48 and the inner wall 50 when theinner structural member 19 and the middle structural member 20 arelocated in the closest relation.

A drain channel 26 is defined between the inner wall 23 and the firstguide portion 25 for collecting and draining the process liquid used forthe process of the wafer W. An inner recovery channel 27 is definedbetween the first guide portion 25 and the outer wall 24 for collectingand recovering the process liquid used for the process of the wafer W.In other words, the first guide portion 25 is disposed upright betweenthe drain channel 26 and the inner recovery channel 27 to isolate thedrain channel 26 and the inner recovery channel 27 from each other.

An evacuation mechanism 28 is connected to the drain channel 26 fordraining the process liquid collected in the drain channel 26 andforcibly exhausting air from the drain channel 26. As shown in FIG. 1,the evacuation mechanism 28 includes, for example, four evacuationmechanisms 28 disposed equiangularly at an interval of 90 degrees. Asshown in FIG. 3, the evacuation mechanisms 28 each include a stationarytubular member 29 extending through the base 16, an annular spacer 30fixed to an upper end of the stationary tubular member 29, a movabletubular member 31 having an upper end connected to the bottom portion 22of the inner structural member 19 and a lower end portion inserted inthe spacer 30 and the stationary tubular member 29, a communication port32 communicating the movable tubular member 31 to the drain channel 26,and a bellows 33 having an upper end fixed to the bottom portion 22 ofthe inner structural member 19 and a lower end fixed to the spacer 30and covering an outer periphery of the movable tubular member 31.

A pipe 34 extending from a negative pressure source not shown isconnected to a lower end of the stationary tubular member 29. When thestationary tubular member 29 is evacuated through the pipe 34 by anegative pressure generated by the negative pressure source, anatmosphere in the drain channel 26 is sucked into the stationary tubularmember 29 through the movable tubular member 31. Thus, the evacuation ofthe drain channel 26 is achieved. Further, an atmosphere around thewafer W held by the spin chuck 1 is sucked into the drain channel 26thereby to be removed by the evacuation of the drain channel 26. Whenthe process liquid used for the process of the wafer W is collected inthe drain channel 26, the process liquid collected in the drain channel26 is discharged together with the atmosphere from the drain channel 26through the communication port 32, the movable tubular member 31, thestationary tubular member 29 and the pipe 34. The process liquiddischarged together with the atmosphere is separated from the atmosphereby a gas/liquid separator (not shown) disposed in the midst of the pipe34, and drained, for example, into a drain line of a plant in which thesubstrate processing apparatus is installed.

A recovery mechanism 35 is connected to the inner recovery channel 27for recovering the process liquid collected in the inner recoverychannel 27 into a recovery tank not shown. As shown in FIG. 1, therecovery mechanism 35 includes, for example, recovery mechanisms 35disposed in diametrically opposed relation with respect to the spinchuck 1 (symmetrically about the rotation axis C). As shown in FIG. 2,the recovery mechanisms 35 each include a hollow cylindrical insertionmember 36 extending through the base 16, an annular spacer 37 fixed toan upper end of the insertion member 36, a stationary tubular member 38having an upper end portion fixed to an upper surface of the spacer 37and extending downward through the insertion member 36 and the spacer37, a retainer member 39 fixed to the bottom portion 22 of the innerstructural member 19, a movable tubular member 40 having an upper endportion retained by the retainer member 39 and a lower end portioninserted in the stationary tubular member 38, a communication port 41communicating the inside of the movable tubular member 40 to the innerrecovery channel 27, a bellows 42 having an upper end fixed to theretainer member 39 and a lower end fixed to the stationary tubularmember 38 and covering an outer periphery of the movable tubular member40, a joint 43 screwed into a lower end portion of the stationarytubular member 38, a tubular joint surrounding member 44 extendingdownward from a lower end portion of the insertion member 36 andsurrounding the joint 43, and a cap member 45 closing a lower endopening of the joint surrounding member 44.

The cap member 45 has a connection port 46. A recovery pipe 47 extendingfrom the recovery tank is connected to the joint 43 through theconnection port 46. The process liquid collected in the inner recoverychannel 27 is recovered in the recovery tank through the communicationport 41, the movable tubular member 40, the stationary tubular member38, the joint 43 and the recovery pipe 47.

The middle structural member 20 surrounds the spin chuck 1, and has agenerally rotationally symmetrical shape about the rotation axis C ofthe wafer W to be rotated by the spin chuck 1. The middle structuralmember 20 integrally includes a second guide portion 48, a bottomportion 49 having an annular plan shape, a hollow cylindrical inner wall50 projecting upward from an inner peripheral edge of the bottom portion49 and connected to the second guide portion 48, and a hollowcylindrical outer wall 51 projecting upward from an outer peripheraledge of the bottom portion 49.

The second guide member 48 disposes outside the first guide portion 25of the inner structural member 19 and includes a lower edge portion 48 ahaving a hollow cylindrical shape concentric with a lower portion of thefirst guide member 25, an upper edge portion 48 b smoothly arcuatelyextending obliquely upward from an upper edge of the lower edge portion48 a toward the center thereof (toward the rotation axis C of the waferW), and a folded portion 48 c formed by folding a distal edge portion ofthe upper edge portion 48 b downward.

The lower edge portion 48 a is located above the inner recovery channel27. The lower edge portion 48 a is accommodated in the inner recoverychannel 27 in spaced relation with respect to the bottom portion 22 andthe outer wall 24 and the first guide portion 25 of the inner structuralmember 19 when the middle structural member 20 and the inner structuralmember 19 are located in the closest relation.

The upper edge portion 48 b vertically overlaps with the upper edgeportion 25 b of the first guide portion 25 of the inner structuralmember 19. When the middle structural member 20 and the inner structuralmember 19 are located in the closest relation, the upper edge portion 48b is located close to the upper edge portion 25 b of the first guideportion 25 with a very small gap being defined between the upper edgeportion 48 b and the upper edge portion 25 b.

The folded portion 48 c horizontally overlaps with the upper edgeportion 25 b of the first guide portion 25 when the middle structuralmember 20 and the inner structural member 19 are located in the closestrelation.

Further, the upper edge portion 48 b of the second guide portion 48 hasa thickness which is progressively increased toward a lower side, andthe inner wall 50 is connected to an outer peripheral edge of the upperedge portion 48 b. The bottom portion 49, the inner wall 50 and theouter wall 51 cooperatively define an outer recovery channel 52 having agenerally U-shaped cross section for collecting and recovering theprocess liquid used for the process of the wafer W.

The outer recovery channel 52 is connected to a recovery mechanism 53for recovering the process liquid collected in the outer recoverychannel 52 into a recovery tank not shown. As shown in FIG. 2, therecovery mechanism 53 includes a hollow cylindrical insertion member 54extending through the base 16, an annular spacer 55 fixed to an upperend of the insertion member 54, a stationary tubular member 56 having anupper end portion fixed to an upper surface of the spacer 55 andextending downward through the insertion member 54 and the spacer 55, aretainer member 57 fixed to the bottom portion 49 of the middlestructural member 20, a movable tubular member 58 having an upper endportion retained by the retainer member 57 and a lower end portioninserted in the stationary tubular member 56, a communication port 59communicating the inside of the movable tubular member 58 to the outerrecovery channel 52, a bellows 60 having an upper end fixed to theretainer member 57 and a lower end fixed to the stationary tubularmember 56 and covering an outer periphery of the movable tubular member58, a joint 61 screwed into a lower end portion of the stationarytubular member 56, a tubular joint surrounding member 62 extendingdownward from a lower end portion of the insertion member 54 andsurrounding the joint 61, and a cap member 63 closing a lower endopening of the joint surrounding member 62.

The cap member 63 has a connection port 64. A recovery pipe 65 extendingfrom the recovery tank is connected to the joint 61 through theconnection port 64. The process liquid collected in the outer recoverychannel 52 is recovered in the recovery tank through the communicationport 59, the movable tubular member 58, the stationary tubular member56, the joint 61 and the recovery pipe 65.

The outer structural member 21 is provided around the spin chuck 1outside the second guide portion 48 of the middle structural member 20,and has a generally rotationally symmetrical shape about the rotationaxis C of the wafer W to be rotated by the spin chuck 1. The outerstructural member 21 includes a lower edge portion 21 a having a hollowcylindrical shape concentric with the lower edge portion 48 a of thesecond guide member 48, an upper edge portion 21 b smoothly arcuatelyextending obliquely upward from an upper edge of the lower edge portion21 a toward the center thereof (toward the rotation axis C of the waferW), and a folded portion 21 c formed by folding a distal edge portion ofthe upper edge portion 21 b downward.

The lower edge portion 21 a is located above the outer recovery channel52, and has a length such as to be accommodated in the outer recoverychannel 52 in spaced relation with respect to the bottom portion 49 andthe inner wall 50 and the outer wall 51 of the middle structural member20 when the outer structural member 21 and the middle structural member20 are located in the closest relation.

The upper edge portion 21 b vertically overlaps with the upper edgeportion 48 b of the second guide portion 48 of the middle structuralmember 20. When the outer structural member 21 and the middle structuralmember 20 are located in the closest relation, the upper edge portion 21b is located close to the upper edge portion 48 b of the second guideportion 48 with a very small gap being defined between the upper edgeportion 21 b and the upper edge portion 48 b.

The folded portion 21 c horizontally overlaps with the upper edgeportion 48 b of the second guide portion 48 when the outer structuralmember 21 and the middle structural member 20 are located in the closestrelation.

The cup 2 includes a first lift mechanism 66 for moving up and down theinner structural member 19, a second lift mechanism 67 for moving up anddown the middle structural member 20, and a third lift mechanism 68 formoving up and down the outer structural member 21.

As shown in FIG. 1, the first lift mechanism 66 includes, for example,first lift mechanisms 66 disposed in diametrically opposed relation withrespect to the spin chuck 1 (symmetrically about the rotation axis C).As shown in FIG. 4, the first lift mechanisms 66 each include an annularfixing member 69 fixed to a lower surface of the base 16, a ball screwmechanism 70 fixed to the fixing member 69 as extending through the base16, an annular spacer 71 fixed to an upper surface of the base 16, ablock 72 fixed to the bottom portion 22 of the inner structural member19, a coupling member 73 which couples a shaft 84 of the ball screwmechanism 70 to be described later to the block 72, and a bellows 74having an upper end portion fixed to the bottom portion 22 of the innerstructural member 19 and a lower end portion fixed to the spacer 71 andcovering outer peripheries of the block 72, the coupling member 73 andthe shaft 84 of the ball screw mechanism 70.

As shown in FIG. 1, the second lift mechanism 67 includes, for example,second lift mechanisms 67 disposed in diametrically opposed relationwith respect to the spin chuck 1 (symmetrically about the rotation axisC). As shown in FIG. 4, the second lift mechanisms 67 each include anannular fixing member 75 fixed to the lower surface of the base 16, aball screw mechanism 70 fixed to the fixing member 75 as extendingthrough the base 16, an annular spacer 76 fixed to the upper surface ofthe base 16, a coupling block 77 fixed to a side surface of the middlestructural member 20 and coupled to a shaft 84 of the ball screwmechanism 70 to be described later, and a bellows 78 having an upper endportion fixed to the coupling block 77 and a lower end portion fixed tothe spacer 76 and covering an outer periphery of the shaft 84 of theball screw mechanism 70.

As shown in FIG. 1, the third lift mechanism 68 includes, for example,two third lift mechanisms 68 spaced a center angle of 120 degrees aboutthe rotation axis C of the wafer W (see FIG. 2). As shown in FIG. 3, thethird lift mechanisms 68 each include a hollow cylindrical spacer 79fixed to the upper surface of the base 16, a coupling block 80 fixed toa side surface of the outer structural member 21 and coupled to a shaft84 of a ball screw mechanism 70 to be described later, and a bellows 81having an upper end portion fixed to the coupling block 80 and a lowerend portion fixed to the spacer 79 and covering an outer periphery ofthe shaft 84 of the ball screw mechanism 70. In each of the third liftmechanisms 68, the ball screw mechanism 70 is fixed to a fixing member(not shown) fixed to the lower surface of the base 16 as extendingthrough the base 16 as in the first lift mechanisms 66 and the secondlift mechanisms 67.

FIG. 5 is a sectional view illustrating a construction of the ball screwmechanism 70.

The ball screw mechanisms 70 each include a retainer tube 82, a ballspline bearing 83 engaged with an upper end portion of the retainer tube82, and the shaft 84 which is retained by the ball spline bearing 83 ina longitudinally movable manner.

The retainer tube 82 has a flange 85 provided around the upper endportion thereof as projecting outward from an outer peripheral surfacethereof. Bolts 86 extending through the flange 85 are screwed into thefixing member 69, 75 (see FIG. 4), whereby the retainer tube 82 is fixedto the fixing member 69, 75.

The shaft 84 has a thread groove 87 provided on an outer peripheralsurface of a lower half portion thereof. A nut 88 is threadingly engagedwith the thread groove 87. The shaft 84 extends in a rotatable mannerthrough a pulley 89 to which a torque of a motor 91, 92, 93 to bedescribed later is inputted. The pulley 89 is fixed to the nut 88 bybolts 90 so as not to rotate relative to the nut 88. Accordingly, whenthe torque is inputted to the pulley 89, the nut 88 is rotated togetherwith the pulley 89, and the rotation of the nut 88 is converted to alinear motion of the shaft 84 by the thread groove 87. Thus, the shaft84 is vertically linearly moved.

FIG. 6 is a simplified plan view illustrating an arrangement fortransmitting driving forces to the first lift mechanisms 66, the secondlift mechanisms 67 and the third lift mechanisms 68.

In the substrate processing apparatus, the motors 91, 92, 93 arerespectively provided for the two first lift mechanisms 66, for the twosecond lift mechanisms 67 and for the two third lift mechanisms 68.

The motor 91 is disposed in the vicinity of one of the two first liftmechanisms 66. A motor pulley 95 is fixed to an output shaft 94 of themotor 91. An endless belt 96 is entrained around the motor pulley 95.The belt 96 is also entrained around the pulley 89 of the ball screwmechanism 70 provided in the other first lift mechanism 66 (disposedapart from the motor 91). The pulley 89 of the ball screw mechanism 70of the one first lift mechanism 66 provided in the vicinity of the motorpulley 95 is held by the belt 96 from opposite sides thereof. Further,two tension pulleys 97 are provided in association with each of thefirst lift mechanisms 66. These tension pulleys 97 apply a tensile forceto the belt 96 so as to prevent the belt 96 from slipping on the pulleys89 and the motor pulley 95.

The motor 92 is disposed in the vicinity of one of the two second liftmechanisms 67. A motor pulley 99 is fixed to an output shaft 98 of themotor 92. An endless belt 100 is entrained around the motor pulley 99.The belt 100 is also entrained around the pulley 89 of the ball screwmechanism 70 provided in the other second lift mechanism 67 (disposedapart from the motor 92). The pulley 89 of the ball screw mechanism 70of the one second lift mechanism 67 provided in the vicinity of themotor pulley 99 is held by the belt 100 from opposite sides thereof.Further, two tension pulleys 101 are provided in association with eachof the second lift mechanisms 67. These tension pulleys 101 apply atensile force to the belt 100 so as to prevent the belt 100 fromslipping on the pulleys 89 and the motor pulley 99.

The motor 93 is disposed in the vicinity of one of the two third liftmechanisms 68. A motor pulley 103 is fixed to an output shaft 102 of themotor 93. An endless belt 104 is entrained around the motor pulley 103.The belt 104 is also entrained around the pulley 89 of the ball screwmechanism 70 provided in the other third lift mechanism 68 (disposedapart from the motor 93). The pulley 89 of the ball screw mechanism 70of the one third lift mechanism 68 provided in the vicinity of the motorpulley 103 is held by the belt 104 from opposite sides thereof. Further,two tension pulleys 105 are provided in association with each of thethird lift mechanisms 68. These tension pulleys 105 apply a tensileforce to the belt 104 so as to prevent the belt 104 from slipping on thepulleys 89 and the motor pulley 103.

Thus, torques generated by the motors 91, 92, 93 are respectivelyinputted to the first lift mechanisms 66, the second lift mechanisms 67and the third lift mechanisms 68 by individually driving the motors 91,92, 93. Thus, the inner structural member 19, the middle structuralmember 20 and the outer structural member 21 are independently moved upand down by the first lift mechanisms 66, the second lift mechanisms 67and the third lift mechanisms 68.

The substrate processing apparatus further has a controlling section 106including a microprocessor. The controlling section 106 controls themotors 91, 92, 93 so as to locate the inner structural member 19, themiddle structural member 20 and the outer structural member 21 at properpositions in individual steps of the process of the wafer W.

FIGS. 7 to 10 are schematic sectional views for explaining the positionsof the inner structural member 19, the middle structural member 20 andthe outer structural member 21 in the individual steps of the process ofthe wafer W.

During the process of the wafer W, the drain channel 26 is constantlyevacuated by the evacuation mechanism 28.

Before the loading of the wafer W, the inner structural member 19, themiddle structural member 20 and the outer structural member 21 arelocated at the lowermost position as shown in FIG. 7. At this time, theupper edge portion 25 b of the first guide portion 25 of the innerstructural member 19, the upper edge portion 48 b of the second guideportion 48 of the middle structural member 20 and the upper edge portion21 b of the outer structural member 21 are located at a lower level thana wafer holding position at which the wafer W is held by the spin chuck1.

When the wafer W is loaded to be held by the spin chuck 1, only theouter structural member 21 is moved up, whereby the upper edge portion21 b of the outer structural member 21 is located at a higher level thanthe wafer W held by the spin chuck 1 as shown in FIG. 8. Thus, anopening is defined between the upper edge portion 48 b of the secondguide member 48 of the middle structural member 20 and the upper edgeportion 21 b of the outer structural member 21 in opposed relation tothe peripheral edge surface of the wafer W.

Thereafter, the wafer W (spin chuck 1) is rotated, and the firstchemical is supplied to the front and rear surfaces of the rotatingwafer W from the nozzle 3 and the rear surface nozzle 8, respectively.The first chemical supplied to the front and rear surfaces of the waferW receives a centrifugal force generated by the rotation of the wafer Wto flow over the front and rear surfaces of the wafer W, and isscattered radially outward from the peripheral edge of the wafer W.Thus, the first chemical is spread over the front and rear surfaces ofthe wafer W, whereby the process of the front and rear surfaces of thewafer W with the first chemical is achieved.

The first chemical spun out to be scattered radially outward from theperipheral edge of the wafer W enters the opening between the upper edgeportion 48 b of the second guide portion 48 of the middle structuralmember 20 and the upper edge portion 21 b of the outer structural member21. Then, the first chemical flows down along an inner surface of theouter structural member 21 to be collected in the outer recovery channel52 and recovered from the outer recovery channel 52 into the recoverytank through the recovery mechanism 53. At this time, the innerstructural member 19 and the middle structural member 20 are located inclose relation with the very small gap being defined between the upperedge portion 25 b of the first guide portion 25 of the inner structuralmember 19 and the upper edge portion 48 b of the second guide portion 48of the middle structural member 20, and the folded portion 48 c of thesecond guide portion 48 horizontally overlaps with the upper edgeportion 25 b of the first guide portion 25, whereby the process liquidis prevented from intruding into a space between the first guide portion25 and the second guide portion 48.

After the first chemical is supplied to the wafer W for a predeterminedperiod, the inner structural member 19 and the middle structural member20 are moved up, so that the upper edge portion 25 b of the first guideportion 25 of the inner structural member 19, the upper edge portion 48b of the second guide portion 48 of the middle structural member 20 andthe upper edge portion 21 b of the outer structural member 21 arelocated at a higher level than the wafer W held by the spin chuck 1 asshown in FIG. 9. At this time, the inner structural member 19 and themiddle structural member 20 are moved up in synchronization with thevery small gap being defined between the upper edge portion 25 b of thefirst guide portion 25 of the inner structural member 19 and the upperedge portion 48 b of the second guide portion 48 of the middlestructural member 20 (while being kept in a predetermined positionalrelation). Thus, the process liquid scattered from the wafer W isprevented from intruding into the space between the first guide portion25 and the second guide portion 48 even when the rotation of the wafer Wby the spin chuck 1 and the supply of the first chemical are continued.

Thereafter, the supply of the first chemical from the nozzle 3 and therear surface nozzle 8 is stopped. Then, the pure water is supplied tothe front and rear surfaces of the wafer W from the nozzle 3 and therear surface nozzle 8, respectively. Thus, the rinsing operation isperformed to rinse the front and rear surfaces of the wafer W with thepure water. The pure water supplied to the front and rear surfaces ofthe wafer W receives a centrifugal force generated by the rotation ofthe wafer W to flow over the front and rear surfaces of the wafer W. Atthis time, the first chemical adhering to the front and rear surfaces ofthe wafer W is rinsed away. Then, the pure water containing the firstchemical is spun out from the peripheral edge of the wafer W to bescattered.

The pure water (containing the first chemical) spun out to be scatteredradially outward from the peripheral edge of the wafer W is captured byan inner surface of the first guide portion 25 of the inner structuralmember 19. Then, the pure water flows down along the inner surface ofthe inner structural member 19 to be collected in the drain channel 26,and is discharged together with the atmosphere of the drain channel 26by the evacuation mechanism 28. At this time, the inner structuralmember 19, the middle structural member 20 and the outer structuralmember 21 are located in close relation with the very small gaps beingdefined between the upper edge portions of the inner structural member19 and the middle structural member 20 and between the upper edgeportions of the middle structural member 20 and the outer structuralmember 21. Further, the folded portion 21 c of the outer structuralmember 21 horizontally overlaps with the upper edge portion 48 b of thesecond guide portion 48, and the folded portion 48 c of the second guideportion 48 horizontally overlaps with the upper edge portion 25 b of thefirst guide portion 25. Thus, the process liquid is prevented fromintruding into the space between the first guide portion 25 and thesecond guide portion 48 and a space between the second guide portion 48and the outer structural member 21.

After the pure water is supplied to the wafer W for a predeterminedperiod, the supply of the pure water from the nozzle 3 and the rearsurface nozzle 8 is stopped. Then, the inner structural member 19, themiddle structural member 20 and the outer structural member 21 are moveddown to the lowermost position, whereby the upper edge portion 25 b ofthe first guide portion 25 of the inner structural member 19, the upperedge portion 48 b of the second guide portion 48 of the middlestructural member 20 and the upper edge portion 21 b of the outerstructural member 21 are located at a lower level than the wafer W.Thereafter, the rotation speed of the wafer W (spin chuck 1) isincreased to a predetermined high rotation speed to perform a dryingoperation for a predetermined period to dry the wafer W by spinning outthe rinse liquid adhering to the surfaces of the rinsed wafer W by acentrifugal force. After the completion of the drying operation, therotation of the wafer W by the spin chuck 1 is stopped, and theprocessed wafer W is unloaded from the spin chuck 1.

Where the wafer W is to be processed with the second chemicalimmediately after the rinsing operation following the process with thefirst chemical, the supply of the pure water from the nozzle 3 and therear surface nozzle 8 is stopped. Thereafter, the inner structuralmember 19 is moved down from the state in which the inner structuralmember 19, the middle structural member 20 and the outer structuralmember 21 are located at the uppermost position, so that only the upperedge portion 25 b of the first guide portion 25 of the inner structuralmember 19 is located at a lower level than the wafer W held by the spinchuck 1 as shown in FIG. 10. Thus, an opening is defined between theupper edge portion of the inner structural member 19 and the upper edgeportion 48 b of the second guide portion 48 of the middle structuralmember 20 in opposed relation to the peripheral edge surface of thewafer W.

Then, the second chemical is supplied to the front and rear surfaces ofthe wafer W rotated continuously from the rinsing operation from thenozzle 3 and the rear surface nozzle 8, respectively. The secondchemical supplied to the front and rear surfaces of the wafer W receivesa centrifugal force generated by the rotation of the wafer W to flowover the front and rear surfaces of the wafer W, and is scatteredradially outward from the peripheral edge of the wafer W. Thus, thesecond chemical is spread over the front and rear surfaces of the waferW, whereby the process of the front and rear surfaces of the wafer Wwith the second chemical is achieved.

The second chemical spun out to be scattered radially outward from theperipheral edge of the wafer W enters the opening between the upper edgeportion 25 b of the first guide portion 25 of the inner structuralmember 19 and the upper edge portion 48 b of the second guide portion 48of the middle structural member 20. Then, the second chemical flows downalong an inner surface of the second guide portion 48 to be collected inthe inner recovery channel 27 and recovered from the inner recoverychannel 27 into the recovery tank through the recovery mechanisms 35. Atthis time, the middle structural member 20 and the outer structuralmember 21 are located in close relation with the very small gap beingdefined between the upper edge portion 48 b of the second guide portion48 of the middle structural member 20 and the upper edge portion 21 b ofthe outer structural member 21, and the folded portion 21 c of the outerstructural member 21 horizontally overlaps with the upper edge portion48 b of the second guide portion 48, whereby the process liquid isprevented from intruding into the space between the second guide portion48 and the outer structural member 21.

After the second chemical is supplied to the wafer W for a predeterminedperiod, the inner structural member 19 is moved up, so that the upperedge portion 25 b of the first guide portion 25 of the inner structuralmember 19, the upper edge portion 48 b of the second guide portion 48 ofthe middle structural member 20 and the upper edge portion 21 b of theouter structural member 21 are located at a higher level than the waferW held by the spin chuck 1 as shown in FIG. 9.

Thereafter, the supply of the second chemical from the nozzle 3 and therear surface nozzle 8 is stopped. Then, the pure water is supplied tothe front and rear surfaces of the wafer W from the nozzle 3 and therear surface nozzle 8, respectively, whereby the rinsing operation isperformed to wash away the second chemical adhering to the front andrear surfaces of the wafer W. In this rinsing operation, the pure water(containing the second chemical) spun out to be scattered radiallyoutward from the peripheral edge of the wafer W is collected in thedrain channel 26 and discharged as in the rinsing operation performedafter the process with the first chemical. Further, the inner structuralmember 19, the middle structural member 20 and the outer structuralmember 21 are located in close relation with the very small gaps beingdefined between the upper edge portions of the inner structural member19 and the middle structural member 20 and between the upper edgeportions of the middle structural member 20 and the outer structuralmember 21. Further, the folded portion 21 c of the outer structuralmember 21 horizontally overlaps with the upper edge portion 48 b of thesecond guide portion 48, and the folded portion 48 c of the second guideportion 48 horizontally overlaps with the upper edge portion 25 b of thefirst guide portion 25. Thus, the process liquid is prevented fromintruding into the space between the first guide portion 25 and thesecond guide portion 48 and the space between the second guide portion48 and the outer structural member 21.

After the pure water is supplied to the wafer W for a predeterminedperiod, the supply of the pure water from the nozzle 3 and the rearsurface nozzle 8 is stopped. Then, the inner structural member 19, themiddle structural member 20 and the outer structural member 21 are moveddown to the lowermost position, whereby the upper edge portion 25 b ofthe first guide member 25 of the inner structural member 19, the upperedge portion 48 b of the second guide portion 48 of the middlestructural member 20 and the upper edge portion 21 b of the outerstructural member 21 are located at a lower level than the wafer W asshown in FIG. 7. Thereafter, the rotation speed of the wafer W (spinchuck 1) is increased to the predetermined high rotation speed toperform the drying operation for a predetermined period to dry the waferW by spinning out the rinse liquid adhering to the surfaces of therinsed wafer W by a centrifugal force. After the completion of thedrying operation, the rotation of the wafer W by the spin chuck 1 isstopped, and the processed wafer W is unloaded from the spin chuck 1.

In the substrate processing apparatus, as describe above, the innerstructural member 19, the middle structural member 20 and the outerstructural member 21 can be moved up and down independently of eachother. This makes it possible to locate the upper edge portions of theinner structural member 19, the middle structural member 20 and theouter structural member 21 at a higher level than the wafer W held bythe spin chuck 1, to locate only the upper edge portion 21 b of theouter structure member 21 at a higher level than the wafer W held by thespin chuck 1, to locate only the upper edge portion 25 b of the firstguide portion 25 of the inner structural member 19 at a lower level thanthe wafer W held by the spin chuck 1, and to locate the upper edgeportions of the inner structural member 19, the middle structural member20 and the outer structural member 21 at a lower level than the wafer Wheld by the spin chuck 1 by moving up and down the structural members19, 20, 21.

During the supply of the first chemical to the wafer W, only the upperedge portion 21 b of the outer structural member 21 is located at ahigher level than the wafer W held by the spin chuck 1. Thus, theopening is defined between the upper edge portion 48 b of the secondguide portion 48 of the middle structural member 20 and the upper edgeportion 21 b of the outer structural member 21 in opposed relation tothe peripheral edge surface of the wafer W, so that the first chemicalspun out to be scattered radially outward from the peripheral edge ofthe wafer W can be introduced into the space between the middlestructural member 20 and the outer structural member 21. Then, theintroduced first chemical is guided by the outer structural member 21 tobe collected in the outer recovery channel 52 and recovered from theouter recovery channel 52 into the recovery tank through the recoverymechanism 53.

In addition, the outer recovery channel 52 in which the first chemicalis recovered is isolated from the inner recovery channel 27 as shown inFIG. 8 during the supply of the first chemical to the wafer W (duringthe recovery of the first chemical), which eliminates the possibilitythat the second chemical flows into the outer recovery channel 52 fromthe inner recovery channel 27 due to the capillary phenomenon.Therefore, a process liquid different from the first chemical isprevented from flowing into the outer recovery channel 52. As a result,the purity of the first chemical recovered in the outer recovery channel52 can be improved.

During the supply of the second chemical to the wafer W, only the upperedge portion 25 b of the first guide portion 25 of the inner structuralmember 19 is located at a lower level than the wafer W held by the spinchuck 1. Thus, the opening is defined between the upper edge portion ofthe inner structural member 19 and the upper edge portion 48 b of thesecond guide portion 48 of the middle structural member 20 in opposedrelation to the peripheral edge surface of the wafer W, so that thesecond chemical spun out to be scattered radially outward from theperipheral edge of the wafer W can be introduced into the space betweenthe inner structural member 19 and the middle structural member 20.Then, the introduced second chemical is guided by the middle structuralmember 20 to be collected in the inner recovery channel 27 and recoveredfrom the inner recovery channel 27 into the recovery tank through therecovery mechanisms 35.

In addition, the inner recovery channel 27 in which the second chemicalis recovered is isolated from the outer recovery channel 52 as shown inFIG. 10 during the supply of the second chemical to the wafer W (duringthe recovery of the second chemical), which eliminates the possibilitythat the first chemical flows into the inner recovery channel 27 fromthe outer recovery channel 52 due to the capillary phenomenon.Therefore, a process liquid different from the second chemical isprevented from flowing into the inner recovery channel 27. As a result,the purity of the second chemical recovered in the inner recoverychannel 27 can be improved.

During the supply of the pure water to the wafer W, the upper edgeportions of the inner structural member 19, the middle structural member20 and the outer structural member 21 are located at a higher level thanthe wafer W held by the spin chuck 1. Thus, the pure water scatteredradially outward from the wafer W is captured by the inner surface ofthe first guide portion 25 of the inner structural member 19, and guidedby the first guide portion 25 to be collected in the drain channel 26.At this time, the inner structural member 19, the middle structuralmember 20 and the outer structural member 21 are located in closerelation with the very small gaps being defined between the upper edgeportions of the inner structural member 19 and the middle structuralmember 20 and between the upper edge portions of the middle structuralmember 20 and the outer structural member 21, whereby the process liquidis prevented from intruding into the space between the first guideportion 25 and the second guide portion 48 and the space between thesecond guide portion 48 and the outer structural member 21. Further, theinner structural member 19, the middle structural member 20 and theouter structural member 21 do not contact with each other, whicheliminates the possibility that particles are generated due to thecontact of these members 19, 20, 21 (by abrasion of the members 19, 20,21 due to the contact).

During the supply of the second chemical and the pure water to the waferW, there is no particular need to move up the outer structural member21, but the outer structural member 21 can be located at the sameposition as assumed for guiding and recovering the first chemical.Therefore, there is no need to provide a greater space above the spinchuck 1, the height of the apparatus is correspondingly reduced.

By the folded portion 21 c of the outer structural member 21, a processliquid different from the first chemical is prevented from intrudinginto the space between the second guide portion 48 and the outerstructural member 21. By the folded portion 48 c of the second guideportion 48 of the middle structural member 20, a process liquiddifferent from the second chemical is prevented from intruding into thespace between the first guide portion 25 and the second guide portion48. Therefore, the purity of the first chemical recovered in the outerrecovery channel 52 and the purity of the second chemical recovered inthe inner recovery channel 27 can be further improved. In addition, thefolded portion 21 c and the folded portion 48 c are respectively unitarywith the outer structural member 21 and the middle structural member 20.Therefore, the construction of the apparatus can be simplified withoutincrease in the number of the components.

When the process is shifted from the first chemical process step to therinsing step, the inner structural member 19 and the middle structuralmember 20 are moved up in synchronization with the very small gap beingdefined between the upper edge portion 25 b of the first guide portion25 of the inner structural member 19 and the upper edge portion 48 b ofthe second guide portion 48 of the middle structural member 20.Accordingly, even when the rotation of the wafer W by the spin chuck 1and the supply of the first chemical are continued during the shift, theprocess liquid scattered from the wafer W is prevented from intrudinginto the space between the first guide portion 25 and the second guideportion 48. Therefore, the second chemical guided by the second guideportion 48 and recovered in the inner recovery channel 27 is preventedfrom being contaminated with the first chemical without reduction of theprocess throughput. As a result, the purity of the second chemicalrecovered in the inner recovery channel 27 can be improved. Therefore,the process of the wafer W can be properly performed even by reusing therecovered second chemical.

When the process is shifted from the rinsing step to the drying step,the inner structural member 19, the middle structural member 20 and theouter structural member 21 are moved down in synchronization with thevery small gaps being defined between the upper edge portions 25 b ofthe first guide portion 25 and the upper edge portion 48 b of the secondguide portion 48 and between the upper edge portion 48 b of the secondguide portion 48 and the upper edge portion 21 b of the outer structuralmember 21. Accordingly, even when the rotation of the wafer W by thespin chuck 1 and the supply of the pure water are continued, the purewater scattered from the wafer W is prevented from intruding into thespace between the first guide portion 25 and the second guide portion 48and the space between the second guide portion 48 and the outerstructural member 21. Therefore, where the first or second chemicalguided by the second guide portion 48 or the outer structural member 21is recovered, the recovered first or second chemical is prevented frombeing contaminated with the pure water to be spun out without reductionof the process throughput. As a result, the purities of the recoveredfirst and second chemicals can be improved. Therefore, the process ofthe wafer W can be properly performed even by reusing the recoveredfirst or second chemical.

During the process of the wafer W, the drain channel 26 is constantlyevacuated. Therefore, an atmosphere containing a mist of the pure waterused for washing away the first chemical or the second chemical from thewafer W can be sucked from the periphery of the wafer W into the drainchannel 26 thereby to be removed in the rinsing step.

Since the first guide portion 25 is provided upright between the drainchannel 26 and the inner recovery channel 27, the drain channel 26 andthe inner recovery channel 27 are isolated from each other by the firstguide portion 25. Further, no evacuation mechanism for forced evacuationis connected to the inner recovery channel 27, so that the innerrecovery channel 27 is not forcibly evacuated. Accordingly, even whenthe drain channel 26 is evacuated, the inner recovery channel 27 is notevacuated, so that an air stream flowing into the inner recovery channel27 from the outside does not occur. Therefore, droplets of the purewater and the first chemical are prevented from intruding into the innerrecovery channel 27. This improves the purity of the second chemicalrecovered from the inner recovery channel 27 while permitting the forcedevacuation of the drain channel 26.

When the second chemical is guided by the second guide portion 48, i.e.,when the second chemical is recovered from the inner recovery channel27, the upper edge portion 25 b of the first guide portion 25 is locatedin the vicinity of the spin base 5 of the spin chuck 1, so that a gapbetween the upper edge portion 25 b of the first guide portion 25 andthe spin base 5 is narrowed as shown in FIG. 10. Thus, the secondchemical is prevented from being sucked into the drain channel 26 by thesuction force generated by the evacuation of the drain channel 26.Therefore, the recovery rate of the second chemical can be improved.

A simple arrangement including the first guide portion 25 providedintegrally with the drain channel 26 and the inner recovery channel 27makes it possible to isolate the drain channel 26 and the inner recoverychannel 27 from each other, so that the evacuation of the inner recoverychannel 27 can be prevented which may otherwise occur due to theevacuation of the drain channel 26. As a result, the purity of thesecond chemical recovered in the inner recovery channel 27 can beimproved without complication of the construction and an associated costincrease.

Further, the drain channel 26 and the outer recovery channel 52 areisolated from each other by the second guide portion 48, and a mechanismfor forcibly evacuating the outer recovery channel 52 is not connectedto the outer recovery channel 52. Accordingly, even when the drainchannel 26 is evacuated, the outer recovery channel 52 is not evacuated,so that an air stream flowing into the outer recovery channel 52 fromthe outside does not occur. Therefore, droplets of the pure water andthe second chemical are prevented from intruding into the outer recoverychannel 52. This improves the purity of the first chemical recoveredfrom the outer recovery channel 52 while permitting the forcedevacuation of the drain channel 26.

In addition, when the first chemical is guided by the outer structuralmember 21, i.e., when the first chemical is recovered from the outerrecovery channel 52, the upper edge portion 25 b of the first guideportion 25 and the upper edge portion 48 b of the second guide portion48 are located in the vicinity of the spin base 5 of the spin chuck 1,so that the gap between the upper edge portion 25 b of the first guideportion 25 and the spin base 5 and a gap between the upper edge portion48 b of the second guide portion 48 and the spin base 5 are narrowed asshown in FIG. 8. Thus, the first chemical is prevented from being suckedinto the drain channel 26 by the suction force generated by theevacuation of the drain channel 26. As a result, the recovery rate ofthe first chemical can be improved.

FIG. 11 is a simplified sectional view illustrating a construction of asubstrate processing apparatus according to another embodiment of thepresent invention.

The substrate processing apparatus according to this embodiment isadapted to supply a first chemical, a second chemical, a third chemicaland pure water as a process liquid in a predetermined order to a wafer Wheld by a spin chuck 1 to perform a cleaning process on the wafer W.

The spin chuck 1 is accommodated in a bottomed hollow cylindrical cup107. A splash guard 108 is provided above the cup 107 vertically movablywith respect to the cup 107.

A drain channel 109 for draining the process liquid used for the processof the wafer W is provided on a bottom portion of the cup 107 annularlyabout a rotation axis C of the wafer W. The drain channel 109 isconnected to an evacuation line 110 for draining the process liquidcollected in the drain channel 109 and forcibly evacuating air from thedrain channel 109. A first recovery channel 111, a second recoverychannel 112 and a third recovery channel 113 each having an annularshape for recovering the process liquid used for the process of thewafer W are provided on the bottom portion of the cup 107 as triplysurrounding the drain channel 109.

The drain channel 109 and the first recovery channel 111 are separatedby a hollow cylindrical partition wall 114 provided therebetween. Thefirst recovery channel 111 and the second recovery channel 112 areseparated by a hollow cylindrical partition wall 115 providedtherebetween, and the second recovery channel 112 and the third recoverychannel 113 are separated by a hollow cylindrical partition wall 116provided therebetween.

The splash guard 108 includes four shade members 117, 118, 119, 120having different sizes and disposed in vertically overlapping relation.A lift mechanism (not shown), for example, including a servo motor, aball screw mechanism and the like is connected to the splash guard 108.The splash guard 108 is moved up and down (vertically) with respect tothe cup 107 by the lift mechanism.

The shade members 117 to 120 each have a generally rotationallysymmetrical shape about the rotation axis of the wafer W.

The shade member 117 includes a hollow cylindrical portion 121 having acenter axis aligning with the rotation axis C of the wafer W, an uppertilt portion 122 extending obliquely upward from an upper edge of thecylindrical portion 121 toward the center thereof (toward the rotationaxis C of the wafer W), and a lower tilt portion 123 extending obliquelydownward from the upper edge of the cylindrical portion 121 toward thecenter thereof. A lower edge of the cylindrical portion 121 is locatedabove the first recovery channel 111, and a lower edge of the lower tiltportion 123 is located above the drain channel 109. The cylindricalportion 121 and the lower tilt portion 123 each have a length such thatthe lower edge thereof is not brought into contact with a bottom surfaceof the cup 107 when the splash guard 108 is moved down to the lowermostretracted position.

The shade member 118 is provided around the cylindrical portion 121 ofthe shade member 117. The shade member 118 includes hollow cylindricalportions 124, 125 each having a center axis aligning with the rotationaxis C of the wafer W, a connection portion 126 connecting upper edgesof the cylindrical members 124, 125 and having a generally U-shapedcross section which opens toward the rotation axis of the wafer W, andan upper tilt portion 127 extending obliquely upward from an upper edgeof the connection portion 126 toward the center thereof. A lower edge ofthe cylindrical portion 124 disposed on an inner side (closer to thecenter) is located above the first recovery channel 111, and a loweredge of the cylindrical portion 125 disposed on an outer side is locatedabove the second recovery channel 112. The cylindrical portions 124, 125each have a length such that the lower edge thereof is not brought intocontact with the bottom surface of the cup 107 when the splash guard 108is moved down to the lowermost retracted position.

The shade member 119 is provided around the cylindrical portion 125 ofthe shade member 118. The shade member 119 includes hollow cylindricalportions 128, 129 each having a center axis aligning with the rotationaxis C of the wafer W, and an upper tilt portion 130 extending obliquelyupward toward the center thereof from an upper edge of the cylindricalportion 129 disposed on an outer side. A lower edge of the cylindricalportion 128 disposed on an inner side is located above the secondrecovery channel 112, and a lower edge of the outer cylindrical portion129 is located above the third recovery channel 113. The cylindricalportions 128, 129 each have a length such that the lower edge thereof isnot brought into contact with the bottom surface of the cup 107 when thesplash guard 108 is moved down to the lowermost retracted position.

The shade member 120 is provided around the cylindrical portion 129 ofthe shade member 119. The shade member 120 includes a hollow cylindricalportion 131 having a center axis aligning with the rotation axis C ofthe wafer W, and an upper tilt portion 132 extending obliquely upwardfrom an upper edge of the cylindrical portion 131 toward the centerthereof. The cylindrical portion 131 is located above the third recoverychannel 113, and has a length such that the lower edge thereof is notbrought into contact with the bottom surface of the cup 107 when thesplash guard 108 is moved down to the lowermost retracted position.

Upper edges of the upper tilt portions 122, 127, 130, 132 are located ona cylindrical plane having a center axis aligning with the rotation axisof the wafer W as being spaced vertically along the rotation axis of thewafer W. Thus, an annular first recovery port 133 which receives theprocess liquid (first chemical) scattered from the wafer W is definedbetween the upper edge of the upper tilt portion 122 and the upper edgeof the upper tilt portion 127. Further, an annular second recovery port134 which receives the process liquid (second chemical) scattered fromthe wafer W is defined between the upper edge of the upper tilt portion127 and the upper edge of the upper tilt portion 130, and an annularthird recovery port 135 which receives the process liquid (thirdchemical) scattered from the wafer W is defined between the upper edgeof the upper tilt portion 130 and the upper edge of the upper tiltportion 132.

A bellows 137 is provided between the lower tilt portion 123 of theshade member 117 and the partition wall 114. Upper and lower edgeportions of the bellows 137 are respectively connected to a lower edgeportion of the lower tilt portion 123 and an upper edge portion of thepartition wall 114. A bellows 138 is provided between the innercylindrical portion 124 of the shade member 118 and the partition wall115. Upper and lower edge portions of the bellows 138 are respectivelyconnected to a lower edge portion of the cylindrical portion 124 and anupper edge portion of the partition wall 115. Further, a bellows 139 isprovided between the inner cylindrical portion 128 of the shade member119 and the partition wall 116. Upper and lower edge portion of thebellows 139 are respectively connected to a lower edge of thecylindrical portion 128 and an upper edge of the partition wall 116.Thus, the drain channel 109, the first recovery channel 111, the secondrecovery channel 112 and the third recovery channel 113 are isolatedfrom each other between the cup 107 and the splash guard 108irrespective of the position of the splash guard 108.

With this arrangement, the splash guard 108 is vertically moved to bringthe first recovery port 133 into opposed relation with the peripheraledge surface of the wafer W. When the first chemical is supplied to thewafer W rotated by the spin chuck 1 in this state, the first chemicalscattered from the peripheral edge of the wafer W enters the firstrecovery port 133 thereby to be collected in the first recovery channel111. Then, the first chemical collected in the first recovery channel111 is recovered in a recovery tank through a recovery mechanism (notshown) connected to the first recovery channel 111.

When the second chemical is supplied to the wafer W rotated by the spinchuck 1 with the second recovery port 134 being opposed to theperipheral edge surface of the wafer W, the second chemical scatteredfrom the peripheral edge of the wafer W enters the second recovery port134 and is recovered in a recovery tank from the second recovery channel112.

When the third chemical is supplied to the wafer W rotated by the spinchuck 1 with the third recovery port 135 being opposed to the peripheraledge surface of the wafer W, the third chemical scattered from theperipheral edge of the wafer W enters the third recovery port 135 and isrecovered in a recovery tank from the third recovery channel 113.

In a rinsing step in which the wafer W processed with the firstchemical, the second chemical and the third chemical is rinsed with thepure water, the splash guard 108 is vertically moved to bring a gapbetween the upper tilt portion 122 and the lower tilt portion 123 of theshade member 117 into opposed relation to the peripheral edge surface ofthe wafer W. When the pure water is supplied to the wafer W rotated bythe spin chuck 1 in this state, the pure wafer scattered from the waferW is collected in the drain channel 109 thereby to be dischargedtogether with the atmosphere of the drain channel 109 through theevacuation line 110.

In this step, the drain channel 109 is constantly evacuated, so that anatmosphere containing a mist of the pure water used for washing away thefirst chemical, the second chemical or the third chemical from the waferW is sucked into the drain channel 109 from the periphery of the wafer Wthereby to be removed.

With the provision of the bellows 137, 138, 139, the drain channel 109,the first recovery channel 111, the second recovery channel 112 and thethird recovery channel 113 are isolated from each other. Therefore, evenwhen the drain channel 109 is evacuated, there is no possibility thatthe first recovery channel 111, the second recovery channel 112 and thethird recovery channel 113 are accordingly indirectly evacuated. Hence,air streams flowing into the first recovery channel 111, the secondrecovery channel 112 and the third recovery channel 113 from the outsidedo not occur. This improves the purities of the first chemical recoveredfrom the first recovery channel 111, the second chemical recovered fromthe second recovery channel 112 and the third chemical recovered fromthe third recovery channel 113 while permitting the forced evacuation ofthe drain channel 109.

In addition, the drain channel 109, the first recovery channel 111, thesecond recovery channel 112 and the third recovery channel 113 areisolated from each other by a simple arrangement including the bellows137 provided between the lower tilt portion 123 of the shade member 117and the partition wall 114, the bellows 138 provided between the innercylindrical portion 124 of the shade member 118 and the partition wall115 and the bellows 139 provided between the inner cylindrical portion128 of the shade member 119 and the partition wall 116. Therefore, theapparatus is free from a significant cost increase even with thisarrangement.

In the rinsing step, a large gap is defined between the spin base 5 andthe splash guard 108 as shown in FIG. 11. During the process with thefirst chemical, on the other hand, the upper edge portion of the uppertilt portion 122 of the shade member 117 is located in the vicinity ofthe spin base 5 of the spin chuck 1 with the first recovery port 133being opposed to the peripheral edge surface of the wafer W, whereby thegap between the spin base 5 and the splash guard 108 is narrowed. Thus,the first chemical is prevented from being sucked into the drain channel109 even when the drain channel 109 is evacuated. Therefore, therecovery rate of the first chemical can be improved. Further, the upperedge portion of the upper tilt portion 127 of the shade member 118 islocated in the vicinity of the spin base 5 during the process with thesecond chemical, and the upper tilt portion 130 of the shade member 119is located in the vicinity of the spin base 5 during the process withthe third chemical. Therefore, the second chemical and the thirdchemical, like the first chemical, are prevented from being sucked intothe drain channel 109, so that the recovery rates of the second chemicaland the third chemical can be improved.

While the embodiments of the present invention have thus been describedin detail, it should be understood that these embodiments are merelyillustrative of the technical principles of the present invention butnot limitative of the invention. The spirit and scope of the presentinvention are to be limited only by the appended claims.

In the first embodiment described above, the first chemical, the secondchemical and the pure water are used for the process by way of example,but a third chemical different from the first and second chemicals maybe additionally used for the process of the wafer W, and the thirdchemical used for the process may be recovered. In this case, anadditional structural member having the same construction as the outerstructural member 21 for guiding the third chemical is provided outsidethe outer structural member 21, and a recovery channel for recoveringthe third chemical guided by the additional structural member isprovided in the outer structural member 21. Thus, the existing inner,middle and outer structural members 19, 20, 21 are utilized togetherwith the additional structural member for the process. Therefore, asignificant cost increase can be avoided. Similarly, where four or morechemicals are used for the process of the wafer W and recovered, asignificant cost increase can be avoided by the aforesaid arrangement.That is, the apparatus can be modified so as to recover increased typesof chemicals without a significant cost increase. Further, when theprocess liquid is guided by the inner structural member 19 or the middlestructural member 20, there is no particular need to move up theadditional outermost structural member, thereby preventing the increasein the height of the apparatus.

In the first embodiment described above, the process with the firstchemical is first performed and, after the rinsing operation, theprocess with the second chemical is performed by way of example.Alternatively, the process with the second chemical may be firstperformed and, after the rinsing operation, the process with the firstchemical may be performed. In this case, when the process is shiftedfrom the rinsing step to the process with the second chemical, the innerstructural member 19 and the middle structural member 20 are moved downin synchronization with the very small gap being defined between theupper edge portion 25 b of the first guide portion 25 of the innerstructural member 19 and the upper edge portion 48 b of the second guideportion 48 of the middle structural member 20 from the state in whichthe inner structural member 19, the middle structural member 20 and theouter structural member 21 are located at the uppermost position. Thus,the process liquid (pure water) scattered from the wafer W is preventedfrom intruding into the space between the first guide portion 25 and thesecond guide portion 48 even when the rotation of the wafer W by thespin chuck 1 is continued during the shift. Therefore, the secondchemical guided by the second guide portion 48 and recovered in theinner recovery channel 27 is prevented from being contaminated with thepure water without the reduction of the process throughput. As a result,the purity of the second chemical recovered in the inner recoverychannel 27 can be improved. Thus, the process of the wafer W can beproperly performed even by reusing the recovered second chemical.

In the embodiments described above, the apparatus is adapted to performthe cleaning process on the wafer W by way of example, but the processto be performed by the inventive apparatus is not limited to thecleaning process. For example, the invention is applicable to an etchingprocess apparatus for removing an unnecessary thin film from a surfaceof a wafer W with the use of an etching liquid, a polymer removingapparatus for removing an unnecessary polymer residue from a surface ofa wafer W with the use of a polymer removing chemical, a resist applyingapparatus for applying a resist liquid on a surface of a wafer W forforming a resist film, and a developing apparatus for supplying adeveloping chemical to a surface of a wafer W for developing a resistfilm.

1. A substrate processing apparatus comprising: a substrate holdingmechanism which generally horizontally holds and rotates a substrate; aprocess liquid supplying mechanism for selectively supplying a firstprocess liquid and a second process liquid to the substrate held by thesubstrate holding mechanism; a first guide portion provided around thesubstrate holding mechanism for guiding the first process liquidscattered from the substrate rotated by the substrate holding mechanismto cause the first process liquid to flow down; a second guide portionprovided around the substrate holding mechanism for guiding the secondprocess liquid scattered from the substrate rotated by the substrateholding mechanism to cause the second process liquid to flow down; adrain channel for draining the first process liquid guided by the firstguide portion; a recovery channel for recovering the second processliquid guided by the second guide portion; and an evacuation mechanismfor forcibly evacuating the drain channel, wherein the drain channel andthe recovery channel are atmospherically isolated from each other andthe recovery channel is not forcibly evacuated.
 2. A substrateprocessing apparatus as set forth in claim 1, wherein the first guideportion is movable to a first position at which a relatively small gapis defined between the first guide portion and the substrate holdingmechanism and to a second position at which a relatively large gap isdefined between the first guide portion and the substrate holdingmechanism and, when the second process liquid is guided by the secondguide portion, the first guide portion is located at the first position.3. A substrate processing apparatus as set forth in claim 1, wherein thefirst guide portion is provided between the drain channel and therecovery channel integrally with the drain channel and the recoverychannel.
 4. A substrate processing apparatus as set forth in claim 1,further comprising an isolation member provided between the drainchannel and the recovery channel and connected to the first guideportion, the isolation member being cooperative with the first guideportion to atmospherically isolate the drain channel and the recoverychannel from each other.